LU501313B1

LU501313B1 - Extraction method for separating rare earth from rare earth feed liquor with high aluminum content

Info

Publication number: LU501313B1
Application number: LU501313A
Authority: LU
Inventors: Hongmin Cui
Original assignee: Inst Applied Chemistry Jiangxi Academy Sciences
Priority date: 2022-01-24
Filing date: 2022-01-24
Publication date: 2022-08-09

Abstract

The present disclosure discloses an extraction method for separating rare earth from a rare earth feed liquor with high aluminum content, comprising the following steps of: (1) carrying out liquid-liquid extraction on the feed liquor containing rare earth sulfate and aluminum sulfate with a mixed solution formed by taking N, N-di-n-octyl-3-oxapentanedioic acid monoamide or N, N-di-iso-octyl-3-oxapentanedioic acid monoamide as an extractant and n-heptane as a diluent to obtain a trivalent rare earth-loaded extract liquor and aluminum raffinate; and (2) carrying out back extraction on the trivalent rare earth-loaded extract liquor by using a low-concentration hydrochloric acid solution to obtain trivalent rare earth back extraction liquor and a regenerated organic phase. According to the extraction method, the N,N-di-n-octyl-3-oxapentanedioic acid monoamide or N,N-di-iso-octyl-3-oxapentanedioic acid monoamide extractant has good selectivity on rare earth, and efficient separation and recovery of the rare earth from the rare earth feed liquor with high aluminum content are achieved; and the back extraction acidity of the trivalent rare earth is very low, so that the back extraction acid consumption is remarkably reduced.

Description

EXTRACTION METHOD FOR SEPARATING RARE EARTH FROM RARE 501313

EARTH FEED LIQUOR WITH HIGH ALUMINUM CONTENT TECHNICAL FIELD

[01] The present disclosure relates to the technical field of rare earth separation, in particular to an extraction method for separating rare earth from rare earth feed liquor with high aluminum content.

BACKGROUND ART

[02] With mining of ion-adsorption rare earth ores, the long-term use of ammonium sulfate as a leaching agent has brought serious ammonia nitrogen pollution to a water system of a mining area. In order to solve the problem of ammonia nitrogen pollution from the source, the development of non-ammonium leaching agents with strong selectivity, wide adaptability and strong leaching ability to replace ammonium sulfate is the main trend in the development of leaching agents in the future. The new generation of ion-adsorption rare earth leaching process with aluminum sulfate as an efficient and green leaching agent not only greatly improves the rare earth leaching efficiency and solves the issue of recycling of aluminum-containing mining residue, but also overcomes the risk of a large amount of low-concentration wastewater and landslides caused by residual magnesium ammonium in the tailings. However, when aluminum sulfate is used as a leaching agent to leach ion-adsorption rare earth ores, the rare earth leaching solution has the characteristics of high aluminum/rare earth ratio. Therefore, breaking through the efficient separation technology of rare earth and aluminum is not only the key to realize the efficient recovery of rare earth, but also the key to ensure the efficient utilization of the leaching agent and the recycling of aqueous solution.

[03] At present, methods by purification and ammonium bicarbonate precipitation are commonly used in industrial production to enrich and recover rare earths, but the precipitation process is slow and incomplete, which easily causes a high aluminum content in rare earth concentrates, reduces a grade of the rare earth concentrates, and increases subsequent processing loads. The recovery of rare earths by solvent extraction can not only achieve the purpose of separating rare earths from most impurities, but also play the role of enrichment, and the raffinate after extracting rare earths can be returned to ion-adsorption rare earth ores leaching after mixing a leaching agent. At present, P507 is mostly used for extraction and separation of rare earths, but this system has a high pH value during saponification extraction, and its organic phase is easily emulsified; especially, the rare earth loss of high alumina rare earth leaching solution system is serious.

[04] Therefore, there is an urgent need for an extraction method for separating rare earth from a high-aluminum rare earth feed liquor with a short process flow and a high rare earth recovery.

SUMMARY

[05] The technical problem to be solved by the present disclosure is to overcome the shortcomings mentioned in the above background art, and provide an extraction method 1 for separating rare earth from a high-aluminum-containing rare earth feed liquor with a LU501313 short process and simple operation, which is beneficial to improving the recovery of rare earth.

[06] In order to solve the above technical problem, the technical solution proposed by the present disclosure is as follows: an extraction method for separating rare earth from a rare earth feed liquor with high aluminum content, comprising steps of:

[07] (1) taking a mixed solution of rare earth sulfate and aluminum sulfate as a feed liquor having a pH value of 0 to 4;

[08] (2) extracting the feed liquor in the step (1) by an organic phase composed of N, N-di-n-octyl-3-oxapentanedioic acid monoamide or N, N-di-iso-octyl-3-oxapentanedioic acid monoamide as extractant and n-heptane as a diluent, to obtain a trivalent rare earth-loaded extract liquor and aluminum raffinate; and

[09] (3) carrying out back extraction on the extract liquor obtained in the step (2) with diluted hydrochloric acid as a back extractant to obtain a trivalent rare earth back extraction liquor.

[10] Preferably, in the step (1), the rare earth sulfate solution has a concentration of 1 to 3 mmol/L; and the aluminum sulfate solution has a concentration of 0.05 to 0.5 mol/L.

[11] Preferably, the rare earth sulfate is one or more of La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu and Y.

[12] Preferably, the N-di-n-octyl-3-oxapentanedioic acid monoamide or the N, N-di-iso-octyl-3-oxapentanedioic acid monoamide in n-heptane has a concentration of

0.01 to 0.1 mol/L; and a ratio of the extract liquor to the feed liquor is 1:1 to 1:5.

[13] Preferably, in the step (2), the extraction is performed at a temperature of 20 °C to 50 C.

[14] Preferably, in the step (3), the dilute hydrochloric acid solution has a concentration of 0.001 mol/L to 0.1 mol/L; and a ratio of the dilute hydrochloric acid solution to the extraction liquor is 1:1 to 5:1.

[15] Compared with the prior art, in the present disclosure, the rare earth and aluminum are extracted from sulfuric acid system with the N, N-di-n-octyl-3-oxapentanedioic acid monoamide or the N, N-di-iso-octyl-3-oxapentanedioic acid monoamide, and then the back extraction is carried out by using dilute hydrochloric acid to obtain a trivalent rare earth back extraction liquor. In the present disclosure, the N,N-di-n-octyl-3-oxapentanedioic acid monoamide or N,N-di-iso-octyl-3-oxapentanedioic acid monoamide is taken as an extractant. The extractant has the characteristics of both monoamide and carboxylic acid extractants, and the N atom, carbonyl group and ether group in the structure can form a large x bond, which increases the acidity of the extractant. Therefore, compared with typical carboxylic acid or diamide podether extractants, the extractant still has good extraction performance for rare earth under low pH conditions without producing a third phase, so that the present disclosure provides good separation effect between rare earth and aluminum, high rare earth recovery rate, low acidity and less acid consumption in the back extraction.

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BRIEF DESCRIPTION OF THE DRAWINGS LUS01313

[16] FIG. 1 is a graph showing an extraction rate of trivalent yttrium and trivalent aluminum with different concentrations of DODGAA in Examples 4-6 of the present disclosure.

[17] Fig.2 is a graph showing an extraction rate of trivalent yttrium and trivalent aluminum with different concentrations of DEHDGAA in Examples 7-9 of the present disclosure.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[18] The technical solutions in the examples of the present disclosure are clearly and completely described below. Obviously, the examples described are only a part of examples of the present disclosure, and are not all of examples thereof. The present disclosure provides an extraction method for separating rare earth from a rare earth feed liquor with high aluminum content, comprising steps of:

[19] (1) taking a mixed solution of rare earth sulfate and aluminum sulfate as a feed liquor having a pH value of 0 to 4;

[20] (2) extracting the feed liquor in the step (1) by an organic phase composed of N, N-di-n-octyl-3-oxapentanedioic acid monoamide or N, N-di-iso-octyl-3-oxapentanedioic acid monoamide as an extractant and n-heptane as a diluent, to obtain a trivalent rare earth-loaded extract liquor and aluminum raffinate; and

[21] (3) carrying out back extraction on the extract liquor obtained in the step (2) with diluted hydrochloric acid as a back extractant to obtain a trivalent rare earth back extraction liquor.

[22] In the above extraction and separation process, N, N-di-n-octyl-3-oxapentanedioic acid monoamide or N, N-di-iso-octyl-3-oxapentanedioic acid monoamide is taken as an extractant. Since the extractant preferably reacts with the rare earth ions with a larger ion radius to undergo neutral complexation or cation exchange reaction to form rare earth complexes, and extracts less aluminum ions with a smaller ion radius, thereby improving the separation efficiency of rare earth.

[23] The present disclosure has no special restrictions on the source of the extractant, which is commercially available or can be prepared by a method well known to those skilled in the art. It is preferably prepared according to the following method, comprising: dissolving 50 g of diethylene glycol anhydride in 500 mL of tetrahydrofuran; weighing 94.5 g of di-n-octylamine or di-isooctylamine and dissolving in 100 mL of tetrahydrofuran; adding the di-n-octylamine or di-isooctylamine solution dropwise to the diethylene glycol anhydride solution in an ice water bath and stirring for reaction at room temperature for 24 h; then rotavaping the tetrahydrofuran, dissolving the product in dichloromethane and washing the product with deionized water, followed by drying with anhydrous magnesium sulfate, filtering, and rotavating the solvent to obtain N, N-di-n-octyl-3-oxapentanedioic acid monoamide (DODGAA) or N, N-di-iso-octyl-3-oxapentanedioic acid monoamide (D,FHDGAA ), respectively.

[24] In the present disclosure, the extractant has a concentration of preferably 0.01 to

0.1 mol/L and more preferably 0.05 mol/L; a ratio of the extraction liquor to the feed 3 liquor is preferably 1:1 to 1:5, more preferably 1:4 to 1:5, and most preferably 1:4; and LU501313 the extraction is performed at a temperature of preferably 20 °C to 50 °C, and more preferably 20 °C to 30 °C.

[25] The present disclosure has no special restrictions on the diluent, which can be a diluent well known to those skilled in the art, such as alkanes and aromatic hydrocarbons, and preferably n-heptane.

[26] In the present disclosure, the rare earth elements in the rare earth sulfate solution are one or more of La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu and Y. The rare earth sulfate solution has a concentration of preferably 1 to 3 mmol/L and more preferably 1.5 to 2 mmol/L; the aluminum sulfate solution has a concentration of preferably 0.05 to 0.5 mol/L and more preferably 0.1 to 0.3 mol/L; and the pH value of the feed liquor is preferably controlled to be of 0 to 4.

[27] After the extraction according to the above method, the extraction liquor and raffinate are obtained. The extraction liquor is an organic phase containing trivalent rare earth, and the raffinate is an aqueous phase containing trivalent aluminum; in addition, after the extraction liquid is obtained, a back extraction is carried out with the dilute hydrochloric acid solution as a back extractant for back extraction to obtain a rare earth back extraction liquor. The hydrochloric acid solution has a concentration of preferably

0.001 to 0.1 mol/L, and more preferably 0.05 to 0.1 mol/L; and the ratio of the hydrochloric acid solution to the extract is preferably 1:1 to 5:1 and more preferably 4:1.

[28] In summary, the present disclosure uses DODGAA or D.EHDGAA as the extractant to separate rare earth from the rare earth leaching solution with high aluminum content, and has the following characteristics: good extraction performance for rare earths under lower pH conditions, good interface phenomena with no emulsification; good separation effect of rare earth from aluminum, high recovery of rare earth, and low acidity and low acid consumption in the back extraction.

[29] In order to further explain the technical solution of the present disclosure, the preferred embodiments of the present disclosure are described with reference to the examples.

[30]

[31] Example 1

[32] 50 g of diethylene glycol anhydride was dissolved in 500 mL of tetrahydrofuran;

94.5 g of di-n-octylamine were weighed and dissolved in 100 mL of tetrahydrofuran; a di-n-octylamine solution was added dropwise to the diethylene glycol anhydride solution in an ice water bath and stirred for reaction at room temperature for 24 h; then the tetrahydrofuran was rotavated, the product was dissolved in dichloromethane and washed with deionized water, dried with anhydrous magnesium sulfate and filtered, and the solvent was rotavated to obtain N, N-di-n-octyl-3-oxapentanedioic acid monoamide (DODGAA).

[33] Example 2

[34] 50 g of diethylene glycol anhydride was dissolved in 500 mL of tetrahydrofuran;

94.5 g of di-isooctylamine were weighed and dissolved in 100 mL of tetrahydrofuran; the di-isooctylamine solution was added dropwise to the diethylene glycol anhydride 4 solution in an ice water bath and stirred for reaction at room temperature for 24 h; then LU501313 the tetrahydrofuran was rotavated, the product was dissolved in dichloromethane and washed with deionized water, dried with anhydrous magnesium sulfate and filtered, and the solvent was rotavated to obtain N, N-di-iso-octyl-3-oxapentanedioic acid monoamide (D,EHDGAA).

[35] Example 3

[36] A feed liquor containing trivalent yttrium, trivalent aluminum and sulfuric acid was prepared, wherein the trivalent yttrium had a concentration of 1.5 mmol/L, the trivalent aluminum had a concentration of 0.2 mol/L, and the feed liquor had a pH value of 3.6.

[37] 2 mL of n-heptane solution of 0.05 mol/L DODGAA was used to extract 2 mL of the feed liquor at 25 °C. It was calculated that the extraction rate of yttrium was 100% and the extraction rate of aluminum was 0.43%.

[38] 2 mL of 0.1 mol/L hydrochloric acid solution was used for back extraction of 2 mL of the extraction liquor. It was calculated that the extraction rate of yttrium was

58.61%.

[39] Example 4

[40] 2 mL of n-heptane solution of 0.05 mol/L DODGAA was used to extract 8 mL of the feed liquor at 25 °C. The extraction rates of yttrium and aluminum were calculated. The calculation results of the extraction rates were shown in Table 1 for providing the extraction rate results of Examples 4-6.

[41] 8 mL of 0.1 mol/L hydrochloric acid solution was used for back extraction of 2 mL of the extraction liquor. The extraction rate of yttrium was 83.59%.

[42] Example 5

[43] 2 mL of n-heptane solution of 0.05 mol/L DODGAA was used to extract 8 mL of the feed liquor according to the method of Example 4. The calculation results of the extraction rates were shown in Table 1.

[44] Example 6

[45] 2 mL of n-heptane solution of 0.1 mol/L DODGAA was used to extract 8 mL of the feed liquor according to the method of Example 4. The results of the extraction rates were shown in Table 1.

[46] The extraction rates of yttrium and trivalent aluminum with different concentrations of DODGAA were shown in Fig. 1.

[47] Table 1 Results of the extraction rates of Examples 4-6 Example | Concentration of DODGAA | Extraction rate of | Extraction rate of trivalent (mol/L) trivalent yttrium | aluminum (%) (%) Ce 95

[48] Example 7

[49] 2 mL of n-heptane solution of 0.05 mol/L DEHDGAA was used to extract 8 LU501313 mL of the feed liquor at 25 C. The extraction rates of yttrium and aluminum were calculated. The calculation results of the extraction rates were shown in Table 2 for providing the extraction rate results of Examples 7-9.

[50] 8 mL of 0.1 mol/L hydrochloric acid solution was used for back extraction of 2 mL of the extraction liquor. It was calculated that the extraction rate of yttrium was

89.22%. [S1] Example 8 [S2] 2 mL of n-heptane solution of 0.02 mol/L DEHDGAA was used to extract 8 mL of the feed liquor according to the method of Example 7. The results of the extraction rates were shown in Table 2. [S3] Example 9

[54] 2 mL of n-heptane solution of 0.1 mol/L. D.EHDGAA was used to extract 8 mL of the feed liquor according to the method of Example 7. The results of the extraction rate were shown in Table 2. [S5] The extraction rates of yttrium and trivalent aluminum with different concentrations of DJEHDGAA were shown in Fig. 2. [S6] Table 2 Results of the extraction rates of Examples 7-9 Example 1 Concentration of | Extraction rate of | Extraction rate of D>HDGAA (mol/L) trivalent yttrium (%) trivalent aluminum (%)

EE CA GE CC me [S7] The experimental results showed that the N,N-di-n-octyl-3-oxapentanedioic acid monoamide or N,N-di-iso-octyl-3-oxapentanedioic acid monoamide extractant had good selectivity on rare earth that could preferentially extract rare earths from rare earth feed liquor with high aluminum content, and basically does not extract aluminum. Moreover, the extraction system was not easily emulsified with good interface phenomenon, realizing efficient separation and recovery of the rare earth from the rare earth feed liquor with high aluminum content; and the back extraction acidity of the trivalent rare earth was very low, so that the back extraction acid consumption was remarkably reduced, and the environmental protection input and production cost were reduced.

[S8] The above description of the disclosed examples enables those skilled in the art to realize or use the invention. Various modifications to these examples will be obvious to those skilled in the art, and the general principles defined herein can be achieved in other examples without departing from the spirit or scope of the present disclosure. Therefore, the present disclosure will not be limited to the examples shown herein, but shall accord with the widest scope consistent with the principles and novel characteristics disclosed herein.

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Claims

WHAT IS CLAIMED IS: LUS01313

1. An extraction method for separating rare earth from a rare earth feed liquor with high aluminum content, comprising steps of: (1) taking rare earth sulfate and aluminum sulfate as a feed liquor having a pH value of 0 to 4; (2) extracting the feed liquor in the step (1) with a n-heptane solution of N, N-di-n-octyl-3-oxapentanedioic acid monoamide or N, N-di-iso-octyl-3-oxapentanedioic acid monoamide as an organic phase to obtain a rare earth extraction liquor and aluminum raffinate; and (3) carrying out back extraction on the extract liquor obtained in the step (2) with diluted hydrochloric acid as a back extractant to obtain a rare earth back extraction liquor.

2. The extraction method for separating rare earth from a rare earth feed liquor with high aluminum content according to claim 1, wherein in the step (1), the rare earth sulfate has a concentration of 1 to 3 mmol/L; and the aluminum sulfate has a concentration of 0.05 to 0.5 mol/L.

3. The extraction method for separating rare earth from a rare earth feed liquor with high aluminum content according to claim 1, wherein in the step (1), the rare earth sulfate is one or more of La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu and Y.

4. The extraction method for separating rare earth from a rare earth feed liquor with high aluminum content according to claim 1, wherein in the step (1), the feed liquor has a pH value of 0 to 4.

5. The extraction method for separating rare earth from a rare earth feed liquor with high aluminum content according to claim 1, wherein in the step (2), the N-di-n-octyl-3-oxapentanedioic acid monoamide or the N, N-di-iso-octyl-3-oxapentanedioic acid monoamide has a concentration of 0.01 to 0.1 mol/L; and a ratio of the extract liquor to the feed liquor 1s 1:1 to 1:5.

6. The extraction method for separating rare earth from a rare earth feed liquor with high aluminum content according to claim 1, wherein in the step (2), the extraction is carried out at a temperature of 20 °C to 50 °C.

7. The extraction method for separating rare earth from a rare earth feed liquor with high aluminum content according to claim 1, wherein in the step (3), the dilute hydrochloric acid has a concentration of 0.001 mol/L to 0.1 mol/L; and a ratio of the dilute hydrochloric acid to the extraction liquor is 1:1 to 5:1.

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